assignments unit 3 part 3

Hydrogen and also alkali metals

Alkali earth metals

Nobel gases

Hydrogen and Alkali Metals

Characteristics of group 1 the the routine table.

You are watching: Which is the least reactive metal

· determine theelementsin group 1 that the routine table.

· describe why team 1elementsare really reactive.

· List various other properties the alkalimetals.


You more than likely think ofwateras a problem that can put out fires. But someelementsare for this reason reactive that they burn in water. In fact, they basically explode in water. That’s what is happening in the photograph above. Around 3 pounds of sodium were added to water, and the result was this explosive reaction. Why is salt such a reactive element? In this lesson friend will find out.

The an initial Group

Sodium (Na) is an aspect in group 1 of the regular table the the elements. This team (column) the the table is presented below. It includes the nonmetal hydrogen (H) and also sixmetalsthat space calledalkali metals. Aspects in the same group of the regular table have the same variety of valenceelectrons. These are the electrons in your outerenergy levelthat deserve to be affiliated in chemical reactions. Valence electrons determine many of the properties of one element, so elements in the same group have similar properties. Every the facets in team 1 have just one valence electron. This provides them an extremely reactive.

Q:Why does having just one valence electron make group 1 elements really reactive?

A:With simply one valence electron, team 1 elements are “eager” to shed that electron. Law so enables them to accomplish a full outerenergy leveland preferably stability.


Reactivity of team 1 Elements

Hydrogen is a an extremely reactive gas, and also the alkalimetalsare even more reactive. In fact, they are the most reactive steels and, along with the facets in team 17, are the many reactive of every elements. The reactivity the alkali metals rises from the top to the bottom of the group, for this reason lithium (Li) is the the very least reactive alkali metal and francium (Fr) is the many reactive. Due to the fact that alkali steels are for this reason reactive, they are discovered in nature just in mix with other elements. They often integrate with team 17 elements, i beg your pardon are really “eager” to acquire an electron. In ~ the URL below, you have the right to watch a video clip that shows just just how reactive the alkali metals are.


Other properties of Alkali Metals

Besides being an extremely reactive, alkali metals share a number of other properties.

· Alkali metals are allsolidsat roomtemperature.

· Alkali metals are short in density, and some of lock float onwater.

· Alkali steels are relatively soft. Part are also soft enough to reduced with a knife, like the salt pictured in theFigurebelow.


A Closer Look

Although all group 1 elements share specific properties, such as being very reactive, they are not alike in every way. Three different group 1 facets are defined in much more detail below (Figuresbelow,below, andbelow). Notice the ways in i m sorry they different from one another.


Hydrogen has actually the smallest, lightest atom of every elements. Pure hydrogen is a colorless, odorless, tasteless gas that is nontoxic yet highly flammable. Hydrogen gas exists mainly as diatomic (“two-atom”) molecule (H2), as shown in the diagram on the right. Hydrogen is the many abundant aspect in the universe and also the third most abundant element on Earth, developing mainly in link such together water.

Q:Why execute you think hydrogen gas normally exists as diatomic molecules?

A:Each hydrogen atom has just one electron. Once two hydrogenatomsbond together, they share a pair ofelectrons. The shared electrons to fill their onlyenergy level, offering them the most stable plan of electrons.


Potassium is a soft, silvery steel that ignites explosively in water. It conveniently loses that one valence electron to type positive potassium ions (K+), i m sorry are essential by every living cells. Potassium is so vital for plants that it is found in practically all fertilizers, like the one presented here. Potassium is plentiful in Earth’s crust in minerals such together feldspar.


Francium has actually one the the largest, heaviest atom of every elements. That is one valence electron is much removed native the nucleus, as you can see in the atomic design on the right, so that is quickly removed indigenous the atom. Francium is radioactive and also quickly decays to kind other facets such together radium. This is why francium is very rare in nature. Less than an ounce of francium is existing on earth at any type of given time.

Q:Francium decays too quickly to formcompoundswith various other elements. Which facets to friend think it would bond with if that could?

A:With one valence electron, francium would certainly bond with a halogen element in group 17, which has actually seven valenceelectronsand needs one more to fill its outer power level. Elements in group 17 encompass fluorine and chlorine.


· team 1 that the routine table includes hydrogen and also the alkali metals.

· due to the fact that they have just one valence electron, team 1 elements are very reactive. Together a result, castle are found in nature only in mix with various other elements.

· Alkali metals are allsolidsat roomtemperature. Castle are fairly soft and also low in density.

· indigenous the top to the bottom of team 1, the elements have heavier, much more reactiveatoms.

Explore More

At the complying with URL, click on “Group 1 data and graphs.” usage the data in the team 1 table to fill in the blanks below with eitherincreasesordecreases.


From the height to the bottom of team 1, nature of the alkali metals adjust as follows:

1. Melting allude __________.

2. Boiling suggest __________.

3. Density __________.

4. Atomic radius __________.

5. Variety of electrons __________.


1. What space alkali metals?

2. Why is hydrogen, a nonmetal, placed in the same team as the alkali metals?

3. Define why group 1 aspects often formcompoundswith elements in group 17.

4. Compare and also contrast hydrogen and francium.

Alkaline earth Metals

Characteristics of team 2 of the periodic table.

· determine alkaline Earthmetals.

· list properties that alkaline Earthmetals.

· explain why alkaline Earthmetalsare an extremely reactive.


Sparklers favor the one this girl is holding make festive enhancements to numerous celebrations. You might use castle yourself. Yet watch out if friend do because their flames room really hot! The shining white flames are created when magnesium burns. Magnesium is a light- weight metal that burns in ~ a very hightemperature. Other offers of magnesium encompass flash photography, flares, and fireworks. Magnesium is a metal in group 2 the the regular table, i beg your pardon you will read about in this concept.  

The second Group

Barium (Ba) is among sixelementsin group 2 the the regular table, i beg your pardon is presented below. Elements in this team are calledalkaline earth metals. These steels are silver or gray incolor. They are relatively soft and also low in density, although no as soft and also lightweight as alkali metals. You can watch a brief video introduction come the alkaline earth metals at this URL:http://www.youtube.com/watch?v=DFQPnHkQlZM.


Reactivity the Alkaline planet Metals

All alkaline planet metals have comparable properties because they all have actually two valenceelectrons. Lock readily offer up their 2 valence electrons to achieve a complete outerenergy level, which is the most stable arrangement of electrons. As a result, they are an extremely reactive, although not quite as reactive as the alkali metals in group 1. For example, alkaline earth metals will react through coldwater, however not explosively as alkali steels do. Because of your reactivity, alkaline earth metals never exist together puresubstancesin nature. Instead, castle are constantly found an unified with otherelements.

The reactivity that alkaline planet metals increases from the height to the bottom that the group. That’s since theatomsget bigger from the top to the bottom, so the valenceelectronsare farther from the nucleus. As soon as valence electrons space farther native the nucleus, they are attracted much less strongly by the cell nucleus and an ext easily eliminated from the atom. This provides the atom more reactive.

Q:Alkali metals have actually just one valence electron. Why room alkaline earth metals less reactive 보다 alkali metals?

A:It takes an ext energy to eliminate two valenceelectronsfrom one atom 보다 one valence electron. This makes alkaline planet metals with their two valence electrons less reactive than alkali steels with their one valence electron.

Examples the Alkaline planet Metals

For a far better understanding the alkaline planet metals, let’s take it a closer watch at 2 of them: calcium (Ca) and strontium (Sr). Calcium is a soft, gray, nontoxic alkaline planet metal. Return pure calcium doesn’t exist in nature, calciumcompoundsare really common in Earth’s crust and also in seawater. Calcium is also the many abundant steel in the human body, developing as calcium link such together calcium phosphate and calcium carbonate. This calcium compounds are uncovered in bones and make them hard and also strong. The skeleton that the average adult contains around a kilogram that calcium. Since calcium—like barium—absorbs x-rays, bones present up white in x-ray images. Calcium is an essential component of a healthy and balanced human diet. Great food sources of calcium room pictured inFigurebelow.


Q:What health difficulties might result from a diet short in calcium?

A:Children that don’t get sufficient calcium while your bones are developing may develop a deficiency an illness called rickets, in which their bones room softer 보다 normal and also become bent and stunted. Adults that don’t get enough calcium may build a problem called osteoporosis, in which the bones lose calcium and also become weak and also brittle. Human being with osteoporosis are at high danger of bone fractures.

Strontium is a silver-colored alkaline earth metal that is also softer 보다 calcium. Strontiumcompoundsare rather common and also have a variety of uses—from fireworks to cement to toothpaste. In fireworks, strontium compounds develop deep red explosions. In toothpaste, like the one pictured in theFigurebelow, the link strontium chloride reduces this sensitivity.



· facets in group 2 the the routine table are called alkaline earth metals. They are silvery or gray incolor. They room also reasonably soft and low in density.

· Alkaline planet metals are really reactive because they readily provide up their 2 valence electron to attain a full outerenergy level, which is the many stable plan of electrons. Reactivity rises from the optimal to the bottom that the group.

· instances of alkaline planet metals encompass calcium, i m sorry is necessary for solid bones, and also strontium, i m sorry is used for making cement and other products.

Explore More

At the complying with URL, observe how four various alkaline earth metals reaction withwater. After ~ you clock the video, prize the questions below.


1. Watch the reactions in the video, and then location the alkaline planet metals from most to least reactive v water.

2. What defines the differences in reactivity?

3. Suspect the reactivity of beryllium through water. Whereby would that fit in her ranking?

4. Whatsubstancesare created in every reaction that you it was observed in the video?


1. What room alkaline planet metals? What space their physics properties?

2. Why are alkaline earth metals really reactive?

3. Compare and also contrast the reactivity of beryllium (Be) and barium (Ba).

Noble Gases

Characteristics of group 18 of the periodic table.

· determine the noblegases.

· list properties that noblegases.

· explain the nonreactivity that noblegasesand just how it is concerned theoctet rule.


Okay, helium balloons space light, yet they’re no that light! This fanciful picture serves to make the point that helium is one of the lightestelements. Helium belongs come a team of aspects called the noble gases.

What are Noble Gases?

Noble gasesare nonreactive, nonmetallicelementsin group 18 of the periodic table. Together you deserve to see in the regular table inFigurebelow, noble gases incorporate helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and also radon (Rn). Every noble gases room colorless and odorless. They likewise have lowboilingpoints, explaining why they space gases in ~ roomtemperature. Radon, at the bottom the the group, is radioactive, so that constantly decays to otherelements. For terrific overview of the noble gases, watch the video clip at this URL:


· come learn just how the noble gases to be discovered, go to this URL:http://www.youtube.com/watch?v=ceQMs30D16E.

· come explore certain noble gases, click on their symbols in the regular table at this URL:http://www.ptable.com/.


Q:Based on their place in the regular table (Figureabove), how plenty of valenceelectronsdo friend think noble gases have?

A:The number of valenceelectronsstarts in ~ one for facets in team 1. The then boosts by one indigenous left come right throughout each duration (row) of the routine table for groups 1–2 and 13–18. Therefore, noble gases have eight valence electrons.

Chemical properties of Noble Gases

Noble gases are the least reactive that all known elements. That’s since with eight valenceelectrons, your outer energy levels room full. The only exception is helium, which has just two electrons. However helium also has a full outerenergy level, since its only energy level (energy level 1) deserve to hold a preferably of two electrons. A complete outer power level is the most stable arrangement of electrons. As a result, noble gases can not become more stable by reacting with various other elements and also gaining or shedding valence electrons. Therefore, noble gases room rarely connected inchemical reactionsand almost never formcompoundswith various other elements.

Noble Gases and also theOctet Rule

Because the noble gases space the least reactive of every elements, your eight valence electrons are used as the typical for nonreactivity and also to define how other facets interact. This is declared as the octet (“group of eight”) rule. Follow to this rule,atomsreact to formcompoundsthat enable them to have a group of eight valence electrons choose the noble gases. For example, salt (with one valence electron) reacts with chlorine (with 7 valence electrons) to kind the secure compound salt chloride (table salt). In this reaction, sodium donates an electron and chlorine accepts it, giving each facet an octet the valence electrons.

Some provides of Noble Gases

Did you ever get helium balloons choose those in the opened picture? unequal a balloon filled v air, a balloon filled through helium needs to it is in weighted under so that won’t float far — although girlfriend don’t have to use one elephant!.

Q:Why does a helium balloon float far if it’s not weighted down?

A:Heliumatomshave just twoprotons, twoneutrons, and two electrons, for this reason they have actually less mass than any kind of other atoms other than hydrogen. Together a result, helium is lighter 보다 air, explaining why a helium balloon floats up into the air unless weighted down.

Early incandescent light bulbs, like the one pictured in theFigurebelow, didn’t last an extremely long. The filaments quickly shed out. Although air to be pumped out of the bulb, the wasn’t a complete vacuum. Oxygen in the small amount the air continuing to be inside the light bulb reacted with the metal filament. This corroded the filament and caused dark store on the glass. Pour it until it is full a irradiate bulb with argon gas prevents these problems. That’s why modern light bulbs are filled through argon.

Q:How go argon prevent the problems of beforehand light bulbs?

A:As a noble gas through eight electrons, argon doesn’t react through the steel in the filament. This protects the filament and also keeps the glass blub free of deposits.


Noble gases are likewise used to fill the glass tubes of lighted indications like the one in theFigurebelow. Return noble gases space chemically nonreactive, your electrons can be energized by sending anelectric currentthrough them. Once this happens, the electrons jump to a higherenergy level. As soon as the electrons go back to their original power level, they give off power as light. Various noble gases offer off light of various colors. Neon gives off reddish-orange light, choose the indigenous “Open” in the sign below. Krypton offers off violet light and xenon provides off blue light.



· Noble gases space nonreactive, nonmetallic aspects in group 18 of the routine table.

· Noble gases are the least reactive of all elements. That’s since they have actually eight valence electrons, which to fill their outerenergy level. This is the many stable plan of electrons, so noble gases rarely react with various other elements and formcompounds.

· Theoctet rulestates thatatomsreact to kind compounds that enable them to have actually eight valence electrons favor the noble gases, which room the least reactive elements.

· Noble gases are provided for balloons, light bulbs, and also lighted signs.

Explore More

Watch the video clip about noble gases in ~ the adhering to URL, and also then prize the questions below.


1. Compare and contrast the reactivity that the aspects helium, neon, argon, krypton, and also xenon.

2. Compare the thickness of this noble gases to the thickness of air.

3. Define how the mass of noble gases alters from the optimal to the bottom of team 18.


1. What space noble gases?

2. Define why noble gases space almost totally nonreactive.

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3. What is the octet rule? just how is it concerned noble gases?

4. Hydrogen (H) atoms have one electron and exist together diatomic (“two-atom”) molecules (H2). Helium atoms have actually two electrons and also exist just as solitary helium atoms. Explain why hydrogen and helium differ in this way.